Production of a recombinant polypeptide in a fungal host cell is usually accomplished by constructing an expression cassette in which the DNA coding for the polypeptide is placed under the expression control of a promoter, suitable for the host cell. The expression cassette may be introduced into the host cell, by plasmid- or vector-mediated transformation. Production of the polypeptide may then be achieved by culturing the transformed host cell under inducing conditions necessary for the proper functioning of the promoter contained in the expression cassette.
For each fungal host cell, expression of a coding sequence which has been introduced into the fungal host by transformation and production of recombinant polypeptides encoded by this coding sequence requires the availability of functional promoters. Numerous promoters are already known to be functional in fungal host cells. There are examples of cross-species use of promoters: the promoter of the Aspergillus nidulans (A. nidulans gpdA gene is known to be functional in Aspergillus niger (A. niger) (J. Biotechnol. 1991 January; 17(1):19-33. Intracellular and extracellular production of proteins in Aspergillus under the control of expression signals of the highly expressed A. nidulans gpdA gene. Punt P J, Zegers N D, Busscher M, Pouwels P H, van den Hondel C A.) Another example is the A. niger beta-xylosidase xlnD promoter used in A. niger and A. nidulans Transcriptional regulation of the xylanolytic enzyme system of Aspergillus, van Peij, NNME, PhD-thesis Landbouwuniversiteit Wageningen, the Netherlands, ISBN 90-5808-154-0 and the expression of the Escherichia coli beta-glucuronidase gene in A. niger, A. nidulans and Cladosporium fulvum as described in Curr Genet. 1989 March; 15(3):177-80: Roberts I N, Oliver R P, Punt P J, van den Hondel C A. “Expression of the Escherichia coli beta-glucuronidase gene in industrial and phytopathogenic filamentous fungi”.
However, there is still a need for improved promoters for controlling the expression of introduced genes, for controlling the level of expression of endogenous genes, for controlling the regulation of expression of endogenous genes or for mediating the inactivation of an endogenous gene, or for producing polypeptides, or for combination of the previous applications. These improved promoters may for example be stronger than the previous known ones. They may also be inducible by a specific convenient substrate or compound. Knowing several functional promoters is also an advantage when one envisages to simultaneously over express various genes in a single fungal host. To prevent squelching (titration of specific transcription factors), it is preferable to use multiple distinct promoters, one specific promoter for each gene to be expressed.